This invention relates to improvements in an elevator speed control system.
In elevator systems the elevator car is generally driven through both a mechanical system including an electric motor, a winding mechanism etc. and a rope system and controlled in speed by a speed control system. However, the car actually travels with a time delay relative to a speed pattern provided by the speed control system due to various external disturbances such as a loss occurring in the mechanical system, a time delay inherent to the control system, etc. In order to increase an accuracy with which elevator cars are to land at any desired position, elevator speed control systems generally generate the speed pattern on the basis of time during the acceleration and on the basis of a distance during the deceleration. The speed pattern during the deceleration temporally leads the actual travel of elevator cars and is only accommodated to a region in which the deceleration is effected with the particular acceleration remaining unchanged. In order to make a ride in an elevator car involved more comfortable at and adjacent to both a maximum and a landing speed thereof, an associated speed pattern can be rounded but it has been difficult to provide a speed pattern rendering the ride in the car comfortable in the basis of a precise distance in a speed region in which the speed pattern is rounded. This is because a logic circuitry for generating a speed pattern including turn around positions is too to be put practical use at present.
Accordingly it is an object of the present invention to provide a new and improved elevator speed control system substantially free from the disadvantages of the prior art practice as above described and providing a precise distance-to-speed pattern with a simplified circuit configuration and without the necessity of performing the complicated logic operation.